Photographic receiver elements containing a cobalt(III) ion complex

ABSTRACT

Photographic receiver elements are disclosed which comprise a support having thereon at least one layer containing an unhardened hydrophilic colloid and said elements contain cobalt(III) ion complexes. The receiver elements can be used in combination with a photographic element containing an imagewise distribution of a metal, such as developed silver, to effect imagewise tanning in the receiver element.

United States Patent 1191 McGuckin 1111 3,862,855 Jan. 28,1975

[ 1 PIIOTOGRAPHIC RECEIVER ELEMENTS CONTAINING A COBALTHII) ION COMPLEX [75] Inventor: I-Iugh Gerald McGuckin, Rochester,

[73] Assignee: Eastman Kodak Company,

Rochester, NY.

221 Filed: Dec. 4, 1972 211 Appl. No.2 312,158

[52] U.S. Cl. 117/161 LN, 96/76 R [51] 844d 1/09, C09d 3/48 [58] Field of Search 96/76, 35.1, 94, 95;

[56] References Cited UNITED STATES PATENTS 3,297,440 1/1967 Delzenne 96/35.]

De Hues 96/76 3,482,972 12/1969 ldelson 96/49 3,752,692 8/1973 Young 1 96/76 R27,375 5/1972 Puerckhuuer.... 96/94 Primary IiruminerNorman G. Torchin Assistant Examiner-John L. Goodrow Attorney, Agent, or Firm--G. E. Battist [57] ABSTRACT 21 Claims, N0 Drawings PHOTOGRAPHIC RECEIVER ELEMENTS CONTAINING A COBALTUII') ION. COMPLEX This invention relates to photographic elementsand to processes for forming image records in photographic receiver elements. In one aspect, this invention relates to photographic elements wherein the image record is formedin a hardenedhydrophilic colloid. In another aspect, this invention relates to receiver. elements which can be contacted with aphotographic silver halide element to form the image record-in the receiver element.

It is known in the art to make photographic elements wherein the gelatin is hardened imagewise by a tanning developer. In certain instances, it is known thatphotographic elements containing silver halide emulsions can be tanned where silver develops when they are developed with tanning developers suchas catechol, pyrogallol, 4-phenyl catechol andthelike; processes of this type are disclosed, for example, in Yackel, Reissue 25,885 issued Oct. 19, 1965. In other instances, it was known to tan an unhardenedhydrophilic colloid layer on a support by transfer of oxidized developersof certain types from an element in interfacial contact therewith which contains silver halide and;unhardened hydrophilic colloid; processes ofthis type are disclosed in Yackel et al, U.S. Pat. No. 3,364,024 issued Jan. 16, 1968.

Generally, the processes in the prior art required high levels of silver halide since oxidized tanning developer was produced directly proportional to the amountof.

silver developed. In other, instances, tanning of'an adjacent layer carried on a separate support could not be attained due to the relative immobility of the oxidized tanning developer. Instill other instances, it would be desirable to use a photosensitive element: containing tanned gelatin layers to produce an imagewisedistribution of tanned hydrophilic colloid in a hydrophilic colloid layer carriedon a separate support. In stillother instances, it would be desirable to tan gelatin in the hydrophilic layer without using the tanning developer.

I have now found that photographic receiver elements containing a layer of unhardened hydrophilic colloid and a cobalt(IIl) ion complex in a concentra: tion of at least 0.5 percent by weight of said colloid can be used to provide image records with improved properties and with considerable latitude in the choice of developing agents, processing conditions, etc. Generally, the receiver elements of this invention are used in combination with a photographic element containing a metal salt which preferably has been developed to provide an imagewise distribution of a metal therein. The receiver element is contacted with the element containing the imagewise distribution ofmetal in the presence of an alkaline solution containing a reducing agent which can be a tanning developer, a color-developing agent, or the like. The hydrophilic colloid is imagewisehardened during the process to form an element which can be washed to remove unhardened hydrophilic colloid or can be used directly such as for printing. Gener ally, the receiver elements ofthis invention are substantially free of silver halide such as before interfacial contact with a photographic element.

In one preferred embodiment, the receiver element comprises sufficient nonmetallic opacifyingmaterial to provide a density of at least 0.5 and preferably at least 1.0. The opacifying material can be carbon, dyes, etc.

In another preferred-embodiment, the receiver element comprises a colbalt(lll) ion complex in a concentration ofatleast 0.5 and preferablyat least 1.0 percent by weight of the hydrophilic colloid based on cobalt.

In another embodiment, the receiver element comprises an incorporateddeveloping agent which can be black-and-white-developing agent or a colordeveloping agent.

In another embodiment, the receiver element comprises a photographic color coupler which is an opacifying dye precursor.

In another embodiment, the receiver element com prises ahydrophobic support.

In another embodiment, this invention relates to an improved process for forming an imagewise distributionof tanned hydrophilic colloid in a receiverelement which is processed in contact with a photographic ele ment containing a silver halide emulsion, the improvement comprising the incorporation in said receiverelement of at least 0.5 percent by weight of the hydrophilic colloid based on cobalt of a cobalt(llI) ion complex.

In still another embodiment, I have found good image recordscan be obtained'by placing a photographic element containing an imagewise distribution of a metal in interfacial contact with a receiver elementcomprising a support having thereon an unhardenedhydrophilic colloid wherein a cobalt(III) ion complex and a reducing agent in a liquid medium are present in'said elements. The elements are preferably left in contact for a time sufficientto achieve an imagewise distribution ofhydrophilic colloid having a melting point at least 20 F. higher than other portions of said hydrophilic colloid.

The receiver elements and processes of ths invention provide several advantages over the elements and-processes known in the art. Generally thicker layers of hydrophilic colloid can be tanned with the present process and with the elements of this invention. The photographic element containing the silver halide emulsion need contain only small amounts of silver halide to yield a. highly tanned image in the receiver element, i.e., less than-50 mg./ft. based on silver, to obtain good hardening of high coverages of the hydrophilic colloid. The photographic element containing the lightsensitive metal salt emulsion can contain a hardened emulsion layer without substantially affecting tanning in the receiver element. Moreover, color developers such as aromatic primary amino compounds can be used to develop the silver halide or as reducing agents in the tanning process. Improved hydrophilic images can be made for lithographic printing since the tanning achieved by the use of cobalt(lII) ion complexes appears to provide better tenacity of the hardened areas to a hydrophobic support. Moreover, the present processes provide a mechanism whereby several wash-off image records can be made from a single photographic element.

In certain embodiments, I have found that receiver elements containing a hydrophilic colloid at levels of 2,000 mg./ft. and above can be effectively tanned imagewise. This is quite unexpected since in many priorart systems it was quite difficult to form a good imagewise distribution of a hardened hydrophilic colloid in a receiver element which contained in excess of 200-500 mg./ft of hydrophilic colloid and hardening was achieved by oxidized tanningdevelloper.

In certain preferred embodiments, the receiver elements of this invention contain opacifying materials or precursors for opacifying materials. Thus, after processing, such as after wash-off of the unhardened areas, the retained image will be visible in at least a portion of the light spectrum. The incorporation of opacifying agents in light-sensitive elements, such as those containing silver halide emulsions, was generally undesirable since the opacifying material necessitated much longer exposure times. Since the opacifying material in the present elements is not in the light-sensitive element but is in the receiver element, it is possible to have high-speed recording material and still produce the desired imagewise distribution of hardened hydrophilic colloid having a high density.

The opacifying materials used in the receiver elements are nonmetallic materials. The term nonmetalhe as used herein is understood to mean that the materials are not metals in their zero valent state. However, the opacifying materials can be organometallic or nonmetallic materials and the like.

Typical opacifying materials which are nonmetallic materials and can be used in the receiver elements of this invention include carbon materials such as Molacco Black (TM), etc.; pigments such as C.I. pigment blue C]. No. 74160, C.I. pigment red C.I. No. 15850, C.I. pigment yellow CI. 21090; and the like.

In one mode of operation of this process, a photographic element comprising a light-sensitive metal salt is imagewise-exposed and then developed to produce an imagewise distribution of a metal. The tanning is achieved by effecting interfacial contact of the photographic element, either before or after development, with a receiver element wherein a cobalt(lll) ion complex and a reducing agent are present in said photographic element or said receiver sheet during said interfacial contact. The elements are separated after the desired hardening has been completed, and the receiver element can be either used as it is or can be washed to remove the areas of lower melting point to provide a wash-off image.

The term interfacial contact as used herein is understood to mean that the elements are placed in effective contact wherein materials can diffuse imagewise from the liquid-permeable layers of one element to the liquid-permeable layers of the other element, such as by putting the silver halide emulsion layer of the photographic element in contact with the unhardened hydrophilic colloid of the receiver element.

The receiver elements of this invention can be used to produce either negative-working elements or positive-working elements. Quite unexpectedly I have found, in certain embodiments, if the photosensitive silver halide element is overexposed such as at least 0.6 log E beyond the optimum exposure, a high-density, negative image will be produced in the receiver element with tanning of retained gelatin after wash-off in the areas in contact with the unexposed silver halide emulsion. When the photosensitive silver halide element is underexposed, such as 0.6 log E below optimum exposure, a positive image is obtained, i.e., the hardened hydrophilic colloid is retained after wash-off in the areas in contact with the exposed silver halide.

The cobalt(lll) ion complexes as referred to herein generally are those complexes which feature a cobalt ion which is surrounded by a group of atoms, ions or other molecules which are generally referred to as ligands. The cobalt ion is generally referred to as a Lewis acid and the ligands are Lewis bases. Werner complexes are well-known examples of such complexes. The useful metal salts are typically capable of existing in at least two valent states. In a preferred aspect of the invention, the cobalt complexes are those referred to by American chemists as inert and by European chemists as robust. Particularly useful are complexes of a cobalt ion with a ligand which, when a test sample thereof is dissolved at 0.1 molar concentration at 20 C. in an inert solvent solution also containing 0.1 molar concentration of a tagged ligand of the same species which is uncoordinated, exhibit essentially no exchange of uncoordinated and coordinated ligands for at least 1 minute, and preferably for at least several hours, such as up to 5 hours or more. This test is advantageously conducted under the pH conditions which will be utilized in the practice of the invention. In silver halide photography, this generally will be a pH of over about 8. Many cobalt complexes useful in this invention show essentially no exchange of uncoordinated and coordinated ligands for several days. The definition of "inert" metal complexes and the method of measuring ligand exchange using radioactive isotopes to tag ligands are well-known in the art; see, for example, Taube, Chem. Rev., Vol. 50, p. 69 (1952), and Basolo and Pearson, Mechanisms of Inorganic Reactions, a Study of Metal Complexes and Solutions, 2nd Edition, 1967, published by John Wiley and Sons, p. 141. Further details on measurement of ligand exchange appear in articles by Adamson et al, J. Am. Chem. Soc., Vol. 73, p. 4789 (I951). The inert metal complexes should be contrasted with labile complexes which, when tested by the method described above, have a reaction half-life generally less than 1 minute. Metal chelates are a special type of metal complex in which the same ligand (or molecule) is attached to the central metal ion at two or more different points. The metal chelates generally exhibit somewhat slower ligand exchange than nonchelated complexes. Labile-type chelates may have a halflife of several seconds, or perhaps slightly longer. Generally, the oxidizing agents employed are not reduced to a zero valent metal during the redox reaction.

The metal complexes preferred in accordance with this process are cobalt(lll) ion complexes which have coordination numbers of 6 and are known as octahedral complexes. Most square planar complexes (which have a coordination number of 4) are rather labile, although some Group VIII metal square planar complexes, particularly platinum and palladium square planar complexes, exhibit inertness to rapid ligand exchange.

A wide variety ofligands can be used with a metal ion to form suitable metal complexes. Nearly all Lewis bases (i.e., substances having an unshared pair of electrons) can be ligands in metal complexes. Some typical useful ligands include the halides, e.g., chloride, bromide, fluoride, nitrite, water, amino, etc., as well as such common ligands as those referred to on p. 44 of Basolo et al, supra. The lability of a complex is influenced by the nature of the ligands selected in forming said complex.

Particularly useful cobalt complexes have a coordination number of 6 and have a polyatomic ligand selected from the group consisting of ethylenediamine(en), diethylenetriamine(dien), triethylenetetraamine(trien), ammine(NH nitrate, nitrite, azide, water, carbonate and propylenediamine(tn). Especially useful are the cobalt complexes comprising ammine ligands such as the cobalt hexammine salts. Some specific highly useful cobalt complexes include those having one ofthe following formulas: [Co(NH H' O]X; [Co(NH CO ]X; [Co(NH Cl]X; and [Co(NI-I )4(CO )]X; wherein X represents one or more anions determined by the charge neutralization rule, and X preferably represents polyatomic organic anions.

In certain preferred embodiments, the anions of the complexes are polyatomic anions, and in some highly preferred embodiments are polyatomic organic anions. The anions are associated with the cobalt(III) ion complex in what may be a salt, an outer sphere complex or ion pair; see, for example, p. 34 of Basolo et al, supra. Typical useful polyatomic anions include sulfato groups, nitrate, andthe like. Typical useful polyatomic organic anions include acetate, propionato, methanesulfonato, benzenesulfonato, hexanesulfonato, and the like.

In another embodiment where the cobalt(III) ion complexes are incorporated in the receiver element, they are incorporated as water-insoluble ion pairs. The use of water-insoluble ion pairs of cobalt(III) ion complexes is described in more detail in Bissonette et al, U.S. Ser. No. 307,894 entitled Ion-Paired Cobaltic complexes and Photographic Elements Containing Same, filed Nov. 20, 1972, which is incorporated herein by reference. Generally, these ion pairs comprise a cobalt(lIl) ion complex ion-paired with an anionic organic acid having an equivalent weight of at least 70 based on acid groups. Preferably, the acid groups are sulfonic acid groups.

In certain highly preferred embodiments, the cobalt (III) ion complexes used in this invention contain at least three amine(NH ligands and/or have a net positive charge which is preferably a net charge of +3. A cobalt(lll) ion with six (NH ligands has a net charge of+3. A cobalt(III) ion with five (NH ligands and one chloro ligand has a net charge of +2. A cobalt(lll) ion with two ethylenediamine(en) ligands and two (N azide ligands has a net charge of+l. Generally, the best tanning results have occurred where the cobalt(III) complex has a net charge of +3 and/or where the cobalt(III) complex comprises at least three and preferably at least five ammine ligands.

The hardenable hydrophilic colloids useful in certain embodiments of this invention are those generally known in the photographic art which can be hardened by photographic hardeners such as formaldehyde. In certain preferred embodiments, the hardenable hydrophilic colloid is a material, such as gelatin, which has a melting point of less than 150 F, and preferably less than 120 F., and preferably has a melting point above about 80 F. In another embodiment, the hydrophilic colloid is a material which can be hardened by a photographic hardening agent to provide at least 100 percent lower water solubility of the hardened material at a temperature of 90 F.

The term unhardened hydrophilic colloid as used herein referes to those materials which are capable of substantial further hardening. These materials may possess a small amount of crosslinking or may have been hardened or tanned slightly. However, generally this term refers to those materials which are capable of being further hardened to provide: a melting-point differential between hardened and unhardened hydrophilic colloid of at least 20 F. and preferably at least 40 F. wherein the unhardened hydrophilic colloid has a melting point of less than F. Typical useful hydrophilic colloids include proteinaceous materials such as gelatin and similar materials which can be hardened by photographic hardeners.

The unhardened hydrophilic colloid is generally coated on the support at a coverage of from about 5 to about 3,000 mg./ft. and preferably from 20 to about 2,000 mg./ft.

Generally, it is preferred to use gelatin as the unhardened hydrophilic colloid in the receiver elements ofthis invention. However, it will be appreciated that other photographic binding agents can be used as substitutes in whole or in part for gelatin. Suitable photographic binders include colloidal albumin, cellulose derivatives such as hydroxyethyl cellulose, synthetic resins such as polyvinyl compounds and the like, and preferably the water-soluble and latex polyvinyl compounds. In certain instances, it is desirable to use latex polymers to improve dimensional stability such as, forexample, the alkyl acrylates and alkyl methacrylate polymers. Where the binding agents are used as a substitute for all or part of the gelatin, the layer must still have the properties as defined for the unhardened hydrophilic colloid layer as set forth herein.

In certain embodiments, the receiver elements used in accordance with this invention have supports which have a hydrophobic surface. Elements of this type are desirable to provide a lithographic plate wherein the hardened gelatin will provide a hydrophilic surface and the areas where the colloid is removed will provide a hydrophobic or oleophilic surface. Typical useful hydrophobic supports include materials such as polyethylene, polystyrene, cellulose esters such as cellulose acetate, polyesters, polytetrafluoroethylene, polystyrenebutadiene, etc.

The hydrophobic surface can be treated to obtain ad hesion to the unhardened hydrophilic colloid layer by methods known for improving the adhesion of hydrophilic materials to hydrophobic supports such as electron bombardment, flame-treating, oxidation with sulfuric acid-dichromatic solution, treatment with chlorine gas, hydrogen peroxide, nitric acid, etc.

In addition to preparing tanned images on conventional supports, my process can be used for making plates by means of stencils. The receiver layer can be made by coating the layer containing the cobalt(III) ion complex and the hydrophilic colloid on a porous support such as cloth, silk or highly porous paper and, after being hardened by contacting against the developing exposed silver halide emulsion, the unhardened areas are removed by washing in warm water, leaving the support pervious to a printing ink in the areas wherein the gelatin has been removed. Prints are then made from the resulting stencil in the usual manner using a low-viscosity ink with a result that a large number of positive prints can be made.

The receiver elements of this invention may comprise incorporated developers such as black-and-whitedeveloping agents or color-developing agents. Since the hardening of the hydrophilic colloid does not depend on a tanning developer such as 4-phenyl catechol, etc., generally any reducing agent can be used to develop the silver halide. Likewise, where other photographic metal salts are used, the reducing agent can be incorporated in the photographic element.

lfthe developing agent is incorporated in the receiver element or in the photographic element, the development can be attained by using an alkaline activator.

Typical activator baths useful where the receiver element or the photographic element contain the developing agent include, for example, an aqueous solution of an alkaline material such as sodium carbonate, sodium hydroxide, potassium carbonate, potassium hydroxide, etc. Suitable baths can comprise, for example, an aqueous solution containing about 1 percent sodium hydroxide. The activator or developer solutions may also contain gelatin softeners such as citric acid or urea to aid in removal of unhardened gelatin during the washoff step.

Typical of the activator solutions which can be used in the present processes are those disclosed in U.S. Pat. Nos. 2,596,756, 2,725,298, 2,739,890, 2,763,553, 2,835,575, 2,852,371 and 2,865,745.

The development and tanning processes as referred to herein can be effected by bathing either or both the exposed photographic element and the receiver sheet in the activator solution or developing solution before rolling into contact with each other. Alternatively, a viscous processing solution can be placed between the elements for spreading in a predetermined amount across and in contact with the emulsion side of the photographic element so as to provide all of the solution required for processing. The viscous processing solution can be located in one or more pods or containers which can be readily ruptured when processing is desired.

The photographic elements used in the process of this invention which contain silver halide emulsions can be developed with black-and-white silver halide developing agents or color-developing agents such as aromatic primary amino compounds. The developing agents can be located in the photographic element, the receiver element or the processing solution. In one preferred embodiment, the developing agent is incorporated in the receiver element whereby interactions with the unexposed silver halides are avoided.

In the process of the invention. tanning takes place when a metal is contacted with a cobalt (111) ion complex and a reducing agent. Especially preferred reducing agents are those which reduce silver halide to metallic silver, such as those which are capable of developing imagewise-exposed, light-sensitive photographic silver halide. The reducing agents can be the same compounds which are used to provide the imagewise distribution of the metal in the photographic elements as described above.

Useful black-and-white developing agents which can be used as reducing agents and to develop the silver halide emulsion include those black-and-white developers disclosed in U.S. Pat. Nos. 2,315,966 by Knott issued Apr. 6, 1943, 2,592,368 by Yackel issued Apr. 8, 1952, 2,685,510 by Yackel issued Aug. 3, 1954,

.2,716,059,by Yutzy et al issued Aug. 23, 1955,

2,751,300 by James et al issued June 19, 1956, 3,146,104 by Yackel et al issued Aug. 25, 1964, 3,180,731 by Roman et a1 issued Apr. 27, 1965, 3,276,871 by Abbott issued Oct. 4, 1966, 3,278,307 by Stewart et al issued Oct. 11, 1966, 3,287,129 by Rees et al issued Nov. 22, 1966, 3,291,609 by Porter et al issued Dec. 13, 1966, and 3,301,668 by Humphlett et al issued Jan. 31, 1967.

Typical useful black-and-white developing agents include hydroquinone, catechol, pyrogallol. N-methyl-paminophenol, p-B-hydroxyethylaminophenol, p-aaminoethylaminophenol, N-methyl-N-(B-sulfoamidoethyl)-p-aminophenol, ascorbic acid, p-hydroxyphenylglycine, morpholino hexose reductone, 2,6-dimethyl morpholino hexose reductone, piperidino hexose reductance, piperidino hexose reductone monoacetate, 4-methyl piperidino hexose reductone, pyrrolidino hexose reductone, dimethylamino hexose reductone, N- methylbenzylamino hexose reductone, and the like. The black-and-white developing agents can be used alone or in combination with auxiliary developing agents. In certain aspects, the reducing agents used in this process is an aromatic primary amino-colordeveloping agent such as p-aminophenol or pphenylenediamine. Color-developing agents which can be used include 3-acetamido-4-amino-N,N- diethylaniline, 4-amino-N-ethyl-N-B- hydroxyethylaniline sulfate, N,N-diethyl-pphenylenediamine, 2-amino-5-diethylaminotoluene, N-ethyl-N-fi-methanesulfonamidoethyl-3-methyl-4- aminoaniline, 4-amino-N-ethyl-3-methyl-N-(B-sulfoethyl)aniline, and the like. See Bent et al, JACS, Vol. 73, pp. 3,1003,125 (1951), and Mees and James, The Theory of the Photographic Process, 3rd Edition, 1966, published by MacMillan Co., New York, pp. 278-311, for further typical, useful developing agents.

In one highly preferred embodiment, aromatic primary amino color-developing agents which provide good results in this process are 4-amino-N,N- diethylaniline hydrochloride, 4-amino-3-methyl-N,N- diethylaniline hydrochloride, 4-amino-3-methyl-N- ethyl-N-B-(methanesulfonamido)ethylaniline sulfate hydrate, 4-amino-3-methyl-N-ethyl-N-B- hydroxyethylaniline sulfate, 4-amino-3-dimethylamino- N,N-diethylaniline sulfate hydrate, 4-amino-3- methoxy-N-ethyl-N-B-hydroxyethylaniline hydrochloride, 4-amino-3-/3-(methanesulfonamido)ethyl-N,N- diethylaniline dihydrochloride and 4-amino-N-ethyl-N- (Z-methoxyethyl-m-toluidine di-p-toluene sulfonate.

In those embodiments where color-developing agents are used, a color coupler can be included in the receiver element to produce an image dye. Useful photographic color couplers or image dye-providing color couplers include any compound which reacts (or couples) with the oxidation products of primary aromatic amino developing agent on photographic development to form an image dye, and are nondiffusible in a hydrophilic colloid binder (e.g., gelatin) useful for photographic silver halide, and also those couplers which provide useful image dyes when reacted with oxidized primary aromatic amino developing agents such as by a coupler-release mechanism. The couplers can form diffusible or nondiffusible dyes. Typical preferred color couplers include phenolic, S-pyrazolone and openchain ketomethylene couplers. Specific cyan, megenta and yellow color couplers which can be employed in the practice of this invention are described in Graham et al, U.S. Pat. No. 3,046,129 issued Jan. 24, 1962, column 15, line 45, through column 18, line 51, which disclosure is incorporated herein by reference. Such color couplers can be dispersed in any convenient manner, such as by using the solvents and the techniques described in U.S. Pat. Nos. 2,322,027 by Jelley et al issued June 15, 1943, or 2,801,171 by Fierke et al issued July 30, 1957. When coupler solvents are employed, the most useful weight ratios of color coupler to coupler solvent range from about 1:3 to 1:01. The useful couplers include Fischer-type incorporated couplers such as those described in Fischer, U.S. Pat. No. 1,055,155 issued March 4, 1913, and particularly nondiffusible Fischer-type couplers containing branched carbon chains, e.g., those referred to in the references cited in Frohlich et al, U.S. Pat. No. 2,376,679 issued May 22, 1945, column 2, lines 50-60. Particularly useful in the practice of this invention are the nondiffusible color couplers which form nondiffusible dyes.

In certain preferred embodiments, the incorporated couplers in the receiver elements of this invention are water-insoluble color couplers which are incorporated in a coupler solvent which is preferably a moderately polar solvent. Typical useful solvents include tri-ocresyl phosphate, di-n-butyl phthalate, diethyl lauramide, 2,4-diarylphenol, liquid dye stabilizers as described in an article entitled Improved Photographic Dye Image Stabilizer-Solvent, Product Licensing Index, Vol. 83, pp. 26-29, March 1971, and the like.

The term nondiffusible" used herein as applied to various compounds, and specifically to the couplers and products derived from couplers, has the meaning commonly applied to the term in color photography and denotes materials which for all practical purposes do not migrate nor wander through photographic hydrophilic colloid layers, such as gelatin, particularly during processing in aqueous alkaline solutions. The same meaning is attached to the term immobile". The terms diffusible and mobile have the converse meaning.

The photographic elements used in combination with the receiver sheets of this invention generally comprise a photographic light-sensitive metal salt. The metal salts are those which are capable of being imagewiseexposed to electromagnetic radiation, preferably in the ultraviolet or visible region of the spectrum, to produce an image record which can then be contacted with a reducing agent or appropriately treated to produce an imagewise distribution of a metal which is preferably a catalytically active Group Ib, VIa or VIII metal, and most preferably a noble metal. In certain highly preferred embodiments, the metal salt is a silver salt which is preferably a silver halide, including silver chloride, silver bromide, silver iodide, mixed halides such as silver bromochloride, silver chlorobromoidide and the like. Other silver salts such as silver oxalate, silver-dye complex and the like can also be used.

The silver halide emulsions can, of course, be negative silver halide emulsions, direct-positive silver halide emulsions, reversal silver halide emulsions and the like. Thus, either negativeor positive-working systems based on the emulsion type can be made in accordance with this invention.

The photographic element can also contain a lightsensitive salt other than silver. Materials of this type include metal compounds which yield photolytically produced metal latent image sites (such as metal of gold, copper, iron, tin, mercury, palladium, etc.), as well as those which merely form an electronic charge latent image such as various photoconductors known in the art. The former type of metal compounds include various silver salts (e.g., halides, oxalates, etc.) as known in the art, as well as a variety of nonsilver metal salts such as oxalate, citrate, etc., salts of a Group VIII, Group lb or Group IIb metal, e.g., palladium oxalate, ferric ammonium oxalate, mercury oxalate, ferric ammonium citrate and the like. Nonsilver salts ofthis type and their use are described in U.S. Pat. Nos. 2,750,292 issued June 12, 1956, and 3,597,206 issued Aug. 3, 1971, and British Pat. No. 1,265,844 dated Mar. 8, 1972. Various useful photoconductive compounds include metal oxides, such as' titanium dioxide, antimony trioxide zirconium dioxide, germanium dioxide, indium oxide, stannic oxide, barium titanate, lead oxide, tantalum oxide and tellurium oxide; metal sulfides such as cadmium sulfide, zinc sulfide and stannic sulfide; and metal selenides such as cadmium selenide. Inorganic photoconductors of this type are described further in U.S. Pat. No. 3,121,006 issued Feb. 11, 1964. Preferred photoconductive compounds for use in this invention are oxides and sulfides ofGroup IIb, IVb or lVa metals. Highly preferred are metal oxides, with titanium dioxide providing good results. Thus, preferred photosensitive metal compounds for use herein contain a Group Ib, IIb, IVb, IVa or VIII metal atom as seen in the Periodic Chart of the elements found on p. 30 of Cotton and Wilkinson, Advanced Inorganic Chemistry, 1962 Edition.

After exposure of the elements-next above described, they are treated with a physical developer solution to deposit imagewise a catalytically active metal such as a Group VIII, Group VIa or Group lb metal whichtypically is different from the metal of said photosensitive compound. Useful physical developer solutions contain as the major active ingredient an ionizable salt of a Group Ib, VIa or VIII metal. Physical developer solutions, for use with elements containing a photosensitive metal compound which upon exposure yields photolytically produced metal latent image sites, typically comprise a reducible heavy metal salt (e.g., a reducible salt of such metals as nickel, cobalt, iron, chromium or cop per), a reducing agent for the heavy metal salt (e.g., formaldehyde, sodium hypophosphite, sodium hydrosulfide or potassium borohydride), and a complexing agent for heavy metal ions derived from the reducible heavy metal salt (e.g., a carboxylic acid such as maleic acid, lactic acid, citric acid, aspartic acid or glycolic acid). Such physical developers are extremely stable under storage conditions, but in the presence of catalytic centers are reduced and deposit heavy metal on the catalytic sites. Physical developers compositions of this type, as well as the formulation thereof, are described, for example, in U.S. Pat. No. 3,597,206 which is incorporated herein by reference.

In those instances where the photosensitive metal compound used is a photoconductor as described previously, the deposition of a catalytically active Group Ib, VIa or VIII metal can be accomplished in a variety of ways. For example, a solution ofa suitable metal salt can be applied to the exposed element whereby the trapped electron-hole pairs produced in the exposed areas of the photoconductor interact with the metal ions in solution to cause deposition of metal. Additionally, various electrolytic-deposition techniques can be used as described, for example, in U.S. Pat. No. 3,372,029 issued Mar. 5, 1968. The The term physical development as used in connection with the present invention has reference to any suitable means for imagewise depositing a catalytically active Group 1b, VIa or VIII metal including the various means known in the art of photoconductography (e.g., see U.S. Pat. No. 3,010,883 issued Nov. 28, 1961).

The photographic elements containing either the light-sensitive silver salts or the nonsilver light-sensitive W metal salts can generally be exposed and processed as EXAMPLE 1:

A receiver element is prepared and used to provide a positive image. The receiver element is prepared as follows:

1. polyester support;

2. layer containing gelatin at 1.25 g./m. and

[Co(NH )6]-Cl at 0.16 g./m. 3. layer containing gelatin at 1.00 g./m. and carbon black at 0.60 g./m.

A photographic silver halide element is imagewiseexposed to a line copy negative 4; second to a 7 /ZWan tungsten bulb at 15 inches); the element comprises a polyethylene-coated paper support coated with a layer containing a green-sensitive silver chloridegelatin emulsion, 1-phenyl-3-pyrazolidone, hydroquinone and sodium formaldehyde bisulfite, wherein said layer is hardened with formaldehyde. The exposed element is immersed for 5 seconds in the following activator solution at 21 C. diluted 1:2 with water. The activator is as follows;

water to [liter The photographic silver halide element is then squeegeed with a rubber wiper blade and rolled in emulsion contact with the receiver element by means of stainless-steel pressure rollers.

After l-minute contact at 21 C., the negative and receiver are delaminated. The receiver is then spraywashed and swabbed with a cotton pad under 32-C. water to remove the untanned portions ofthe receiver. in this particular sample, the areas in the receiver corresponding to the developed silver image in the photographic element ar tanned. The untanned areas corrsponding to the unexposed portions are removed by the washing step. A high-density, wash-off carbon image results which is a positive print of the negative original (negative-working). Sensitometric exposure to a 0.15 log E silver step tablet for 3 seconds shows the Dmax to be over 4.0 and the gamma over 13.0.

The above procedures are repeated except the exposure given is increased from V; second (two stops below normal) to 2 seconds (two stops above normal) and the receiver is not swabbed during washing.

A high-density, wash-off carbon image results which is a direct reproduction of the negative original (positive-working). The sensitometrically exposed sample shows the Dmax to be over 4.0 and the gamma over 13.0.

Similar results are obtained when the cobalt(III) ion complexes [Co(NH )4(CO ]NO [Co(N1-I )5(CO3)] N and [Co(NH )-(H O)]( ClO4) are incorporated in the receiver element in place of the [Co(N H )6]Cl;, However, best results occur when the cobalt(11l) complex contains at least 3 amine ligands and/or has a net positive charge of +3.

EXAMPLE 2 A receiver element is prepared as described in Example 1 except methyl violet dye is substituted for the carbon black at a concentration of 0.30 g./m. The exposure of the photographic silver halide element and the processing are carried out as described in Example 1. The results are identical with respect to exposure and image polarity, although the image densities are considerably lower.

EXAMPLE 3 The material and procedures of Example 1 are followed as described, except the negative is given a normal exposure time of 1% second instead of /a second or 2 seconds. A wash-off image which is neither negativenor positive-appearing is produced. This image is observed as clear tanned gelatin characters having a highdensity carbon or fringe.

EXAMPLE 4 A two-layer material of Example 1 is processed as described, except a color-developer solution is substituted for the alkaline activator. A high-density, washoff carbon image is obtained which is a positive print of the negative original (negative-working) when expsure time of A second is given. The color-developer solution is as follows:

benzyl alcohol 1 K SO KBr hydroxylamine sulfate 4-amino-N-ethyl-N-(2-methoxyethyl)-m toluidine dLpara-toluenesulfonate K CO 3 diaminopropanol tetraacetic acid water to 1 liter; pH 10.1

EXAMPLE 5 A receiver element is prepared as follows:

1. transparent polyester support;

2. layer containing gelatin at 2 g./m. [Co(NH )6]Cl at 0.25 g./m. and carbon black at 0.30 g./m.

A photographic silver lhalide element described in Example 1 is exposed and processed as described in Example followed by emulsion contact with the receiver element for 1 minute and spray-washing and swabbing as described in Example 1. The short exposure time (As second) produces a positive washoff image from the negative original, while the long exposure time (2 seconds) results in a direct reproduction of the negative original. The density of resulting coating is about 1.0.

EXAMPLE 6 A single-layer receiver is prepared exactly as described in Example 5 except methyl violet dye is substituted for the carbon black at the same concentration (0.30 g./m. Exposure and processing are also carried out as described in Example 1. The results are similar EXAMPLE 7 A receiver element is prepared as follows:

1. polyester support;

2. containing unhardened gelatin at 500 mg./ft. and

[Co(N1-1 )6]C1 at 67.5 mg./ft.

A sheet of the photographic silver halide element of Example 1, exposed and processed in accordance with Example 1, is rolled in emulsion contact with the receiver element by means of stainless-steel pressure rollers. After 2 minutes contact, the receiver is delaminated from the silver halide-containing element and portions of the receiver element are removed by spraywashing under warm water and immersed for 10 seconds in an image conditioner as described in Connally and Swift, U.S. Pat. No. 3,139,825, and then rinsed. A lithographic ink and water are applied to the image surface using a damp cotton pad. The ink adheres to the washed-off areas (uncovered hydrophobic support) while water is absorbed by the tanned image areas (positive-working). The ink can be readily transferred from the receiver to a sheet of paper.

EXAMPLE 8 A receiver element is prepared as follows:

1. polyester support;

2. layer containing 800 mg./ft. of gelatin, 400

mg./ft. of the cyan color coupler 2-[a-(2,4-di-tertamylphenoxy)butyramido]-4,6-dichloro-- mcthylphenol dispersed in 200mg. of di-n-butyl phythalate, and [Co(NH )6]Cl at 250 mg./ft.

The photographic silver halide elementof Example 1 is exposed as described in Example 1 and processed for 10 seconds at 21 C. in a color-developer solution having the following composition:

sodium sulfite (anhydrous) 4-amino-N-ethyl-N-(Z-methoxyethyl-m-toluidine di-p-toluene sulfonic acid sodium carbonate (monohydrate) 2 potassium bromide o-mercaptobenzoic acid sodium thiosulfate (pentahydrate) water to 1 liter The processed element is then rolled in emulsion contact with the receiver element by means of stainlessteel pressure rollers. After l-minute contact ay 100 F., the silver halide-containing element and receiver element are delaminated. A cyan-colored tanned image is visible in the receiver element in those areas corresponding to the silver image in the silver halidecontaining element. The untanned portions of the receiver element are removed by spray-washing under warm water (-320 C.). The sample is immemmrsed in an image conditioner, as described in U.S. Pat; No. 3,139,825, and rinsed. Lithographic ink and water are then applied to the image surface using a damp cotton pad. The ink adheres to the washed-off areas (uncovered hydrophobic support) while water is absorbed by the tanned image portions (positive-working). The ink can be readily transferred from the receiver to a sheet of paper.

EXAMPLE 9 Several receiver elements are prepared which comprise layers containing cobalt(lll) hexammine chloride at concentrations of 0.16, 0.08, 0.04, 0.02 and 0.0 g./m. respectively, coated in 1.25 g. of gel/ft. on a polyester support as follows:

A sheet of photographic negative element as de' scribed in Example 1 is exposed to a high-contrast, line copy negative 1: second to a 7 /-vvatt tungsten bulb at 15 inches). The exposed negative element is then immersed for 5 seconds in a color developer at 21 C. The developer has the formula shown in Example 4. The negative is then rolled in emulsion contact with the receiver coating by means of stainless-steel pressure rollers. After 2 minutes contact at 21 C., the negative and receiver are delaminated. The receiver is spraywashed under 32C. water to remove the untanned portions (areas adjacent the unexposed portions of the negative during lamination). A 1.0 percent aqueous portions of the negative during lamination). A 1.0 percent aqueous solution of rosanilinehydrochloride dye is applied to the processed receiverin order to amplify The minimum concentration of cobalt(lll) required appears to be at least 0.5 percent and preferably 1.0 percent by weight based on cobalt of the hydrophilic colloid.

EXAMPLE l0 Separate receiver coatings are prepared on polyester support which comprises a layer of gel at 1.25 g./m. containing cobalt hexammine chloride (0.16 g./m. overcoated with a gel layer (1.50 g./m overcoated with a gel layer (1.50 g./m. containing cyan, magenta or yellow pigments (1.00 g./m respectively. Contact exposures are made from halftone silver separation negatives onto a photographic negative element as described in Example 1. The exposed photographic element is immersed in the color developer of Example 4 for 5 seconds at 20 C. and laminated to the receiver containing the appropriate pigment for 2 minutes at 20 C. After separation, the receiver is spray-washed under 32-C. water to remove the untanned portions. A fullcolor halftone reproduction of the original scene is produced by overlaying the cyan, magenta and yellow receiver images. Image quality and color balance appear to be fairly good.

EXAMPLE 1 1 A receiver coating is prepared on polyester support which comprises a layer containing gel at 1.25 g./m. and cobalt hexammine chloride (0.16 g./m. overcoated with a gel layer at 1.00 g./m. which also contains carbon black pigment (0.60 g.lm. A 2.0 percent aqueous solution of hydroquinone is applied to a portion of the coated layers with a cotton pad and allowed to dry.

A photographic negative element containing a silver halide emulsion is exposed to a high-contrast, line copy negative seconds to a 7 /z-watt tungsten bulb at inches). The exposed photographic element is immersed for 5 seconds in an activator at 21 C., as described in Example 1, diluted 1:2 with water.

The negative is rolled in emulsion contact with the receiver coating by means of stainless-steel pressure rollers. After l-minute contact at 21 C., the negative and receiver are delaminated.

The receiver is spray-washed under 35 C. water to remove the untanned portions. lmagewise tanning is observed in the portion of the receiver in which the developing agent has been applied. In those areas a highdensity, wash-off carbon image results. Complete washoff results in those areas of the receiver not containing hydroquinone.

EXAMPLE 12 A receiver coating is prepared on polyester support which is identical to the receiver material described in Example 11 except the cobalt hexammine chloride is omitted. A 2.0 percent aqueous solution of cobalt hexammine acetate is applied to a portion of the coated material with a cotton pad and allowed to dry. The receiver is processed as described in Example 9. A highdensity, wash-off carbon image is produced in the area which contains the cobalt hexammine acetate. There is no indication of image formation formation in the areas without.

EXAMPLE 13 A sample of the receiver material of Example 12 is partially swab-coated with a 2.0 percent aqueous solution of cobalt hexammine acetate as described in Example 12. The receiver is processed as follows:

A sample of a silver halide emulsion coating containing hydroquinone is exposed to a high-contrast, line copy negative for 2 seconds (HQ-watt tungsten bulb at 15 inches). Half of the sample is covered with a 0.9 neutral density filter. The exposed negative is immersed for 5 seconds in an activator solution at 21 C., as described in Example 1, diluted 1:2 with water.

The negative is then squeegeed with a rubber wiper blade and rolled in emulsion contact with the receiver coating by means of stainless-steel pressure rollers. After l-minute contact at 21C., the negative and receiver are delaminated.

The receiver is spray-washed under 35 C. water to remove the untanned portions. The portion of the sample corresponding to low-exposure regions requires swabbing in order to remove the untanned gel. That portion of the receiver corresponding to areas which have been exposed for 2 seconds shows a direct reproduction of the negative original in the area which contains the cobalt hexammine acetate. A low-density, direct reproduction of the negative original (positiveworking) is observed in the area which does not contain cobalt hexammine acetate. The remaining portion which receives three stops less exposure shows a gooddensity, positive-appearing, wash-off carbon image from the negative original (negative-working) in the area which contains cobalt hexammine acetate, while the area which does not contain any cobalt hexammine acetate does not show a wash-off carbon image.

This example demonstrates the enhancement of imagewise tanning by the presence of cobalt(lll) ammine complex in the receiver with hydroquinone incorporated in a film emulsion.

EXAMPLE 14 The receiver materials described in Example 11 (with cobalt hexammine chloride 0.16 g./m. and Example 12 (no cobalt(lll) ammine complex) are compared utilizing an unhardened silver halide emulsion coating containing 4-phenyl catechol.

Both receivers are tested as follows:

A sample of the negative emulsion is exposed to a high-contrast, line copy negative for 1 minute (60-watt tungsten bulb at 15 inches). The exposed negative is immersed in an activator solution at 21 C., as described in Example 1, diluted 1:2 with water.

The receiver is spray-washed under 32 C. water to remove the untanned portions. A wash-off carbon image is obtained with the receiver containing cobalt hexammine chloride. The carbon image washes off entirely from the receiver which does not contain cobalt hexammine chloride.

EXAMPLE 15 Several receiver elements are prepared which contain two layers on a polyester support. The first layer coated contains, respectively, 125, 250, 500 and 1,000 mg. of unhardened gelatin/ft. and 16, 32, 64 and 128 mg. of [Co(NH )6]Cl /ft. Corresponding elements are also prepared which do not contain the cobalt salt. Each element is then overcoated with a layer containing mg./ft. of unhardened gelatin and 60 mg. of carbon black. The receiver elements are processed using a photographic element, exposed and developed as in Example 1, which is then immersed in the activator of Example 1 at 21 C. diluted 1:2 with water for 5 seconds.

The photographic negative element is rolled in emulsion contact with the receiver coating by means of stainless-steel pressure rollers. After a l-minute contact at 21 C., the negative and receiver are delaminated.

The receiver is spray-washed under 35 C. water to remove the untanned portions. Wash-off carbon images are obtained at all levels in the receivers containing cobalt salts. In the elements which do not contain cobalt salts, a good carbon image is obtained only at the mg. level with very weak images at the 250 and 500 mg. levels.

It is apparent that substantially better tanning is obtained in the receiver elements where [Co(Nl-l )6]Cl is present.

EXAMPLE 16:

A receiver element is prepared as follows:

1. polyester support;

2. layer containing unhardened gelatin at 125 mg./ft.

and [Co(NH )6]Cl at 16.9 mg./ft.

A sheet of the photographic silver halide element of Example 1 is exposed in accordance with Example 1. The exposed element is immersed for 5 sec. in the following developer solution at 21 C. The developer is as follows:

H 0 800 ml. benzyl alcohol 4.0 ml. sodium polyphosphate 0.5 g. Na SO, 2.0 g.

-Cont1nued 40% NaOH solution 0.4 ml. 4-amino-3-methyl-N-ethyl-N-B-(methane- 5.0 g.

sulfonamido)ethylaniline sesquisulfate hydrate 50% NaBr solution 1.72 ml.

l'l,0 to 1 liter; pH 10.75

The photographic silver halide element is then rolled in emulsion contact with the receiver element by means of stainlesssteel pressure rollers.

After Z-minute contact at 21 C., the negative and receiver are delaminated and the receiver element is immersed for sec. in an image conditioner as described in Hepher, U.S. Pat. No. 3,161,508. The receiver element is then lightly swabbed with a cotton pad wet with water. The untanned portions of the receiver element appear to remain intact.

The receiver element at this point is utilized as a plate in a lithographic press. A lithographic ink and water are applied to the image surface. The ink adheres to the areas which correspond to the developed silver image in the photographic element while water is absorbed by the remaining areas (negative-working). Ink is readily transferred from the receiver to the paper.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention.

1 claim:

1. A photographic receiver element comprising a support having coated thereon at least 5 mg./ft. of a hydrophilic colloid having a melting point of less than 150 F. and capable of being hardened with formaldehyde to provide a melting point differential between hardened and unhardened areas of at least 20 F and wherein said element contains a cobalt(lll) ion complex having a coordination number of 6 in a concentration of at least 0.5 percent by weight of said hydrophilic colloid based on cobalt.

2. A receiver element according to claim 1 wherein said cobalt(IlI) complex is present in a concentration of at least 1.0 percent by weight of said hydrophilic colloid based on cobalt.

3. A receiver element according to claim 1 wherein said unhardened hydrophilic colloid consists essentially of gelatin at a concentration of at least 20 mg./ft.

4. A receiver element according to claim 1 which contains a nonmetallic opacifying material dispersed in said hydrophilic colloid.

5. A receiver element according to claim 1 which contains an incorporated silver halide developing agent.

6. A receiver element according to claim 1 which I contains a photographic color coupler.

7. A receiver element according to claim 1 wherein said cobalt(lll) ion complex has a net charge of +3.

8. A receiver element according to claim 1 wherein said cobalt(lll) ion complex contains at least 3 ammine ligands.

9. A receiver element according to claim 1 wherein said receiver element is coated on a hydrophobic suport. p 10. A receiver element according to claim 1 which contains a carbon opacifying agent in a concentration to provide a density of at least 0.5.

11. A photographic receiver element comprising a support having coated thereon at least 5 mg./ft. of an unhardened hydrophilic colloid which consists essentially of an unhardened gelatin having a melting point of less than F. and wherein said element contains a cobalt(lll) ion complex in a concentration of at least 1.0 percent by weight of said gelatin based on cobalt, wherein said cobalt(lll) ion complex has a coordination number of 6 and contains at least 3 ammine ligands.

12. A photographic receiver element according to claim 11 which is substantially free of silver halide.

13. A photographic receiver element according to claim 11 which comprises an opacifying material in a quantity sufficient to provide a density of at least 0.5.

14. A photographic receiver element according to claim 11 which contains carbon black dispersed in said gelatin.

15. A photographic receiver element according to claim 11 wherein said cobalt(lll) ion complex is a cobaltic hexammine ion complex.

16. A photographic receiver element according to claim 11 wherein said hydrophilic colloid is an unhardened gelatin at a concentration of 20 mg./ft. to about 2,000 mg./ft.'

17. A photographic receiver element comprising a support having thereon at least one layer containing an unhardened hydrophilic colloid and at least one other layer containing an unhardened hydrophilic colloid and an opacifying material, and wherein said element contains at least 0.5 mg./ft. of a cobalt (III) ion complex and wherein said element contains at least 5 mg./ft. of unhardened hydrophilic colloid and said hydrophilic colloid has a melting point of less than 150 F. and is capable of being hardened with formaldehyde to provide at least a 20 F. melting point: differential between hardened and unhardened areas.

18. A photographic element according to claim 17 wherein said support has coated thereon, in sequence, 1) said layer containing unhardened hydrophilic colloid and 2) said layer containing said unhardened hydrophilic colloid and said opacifying material.

19. A photographic receiver element according to claim 7 wherein said opacifying material is carbon black.

20. A photographic receiver element comprising a support having thereon at least one layer containing an unhardened hydrophilic colloid and at least 0.5 mg./ft. of a cobalt(Ill) ion complex and at least one other layer containing an unhardened hydrophilic colloid and an opacifying material, wherein said element contains at least 20 mg./ft. of unhardened hydrophilic colloid and said hydrophilic colloid has a melting point of less than 150 F. and is capable of being hardened with formaldehyde to provide at least a 20 F. melting point differential between hardened and unhardened areas.

21. A photographic receiver element according to claim 20 wherein said unhardened hydrophilic colloid consists essentially of unhardened gelatin.

uNITEu STATES PATENT AND TRADEMARK OFFICE CERTIFICATE 0F CRRECTKON PATENT NO. 3,862,855 DATED January 28, 1975 INVENTORGQ Hugh Gerald McCuckin It is certified that error appears-in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 2, "colbalt" should read -cobalt--, Column t, line 9, "robust. should read --"robust".,--- Column 5, line 29, "complexes" should read --Complexes-- Column 7, penultimate I line, "3,301,668" should read --3,3o1,678--. Column 8, lines 7-8,

'reductance" should read --reductone-; line l t, "agents" (2nd occurrence) should read --agent--; line 58, "megenta" should read -magenta-. Column 9, line #6, "chlorobromoidide" should read chlorobromoiodide--; line 59, after "metal" (2nd occurrence), imagesshould be inserted, Column 10, line 6, after "trioxide", should be inserted. Column 11, line +7, "ar" should read are--. Column 12, line 2, "amine" should read -ammine--; line 22, after "carbon --border-- should be inserted; line 26, "A" should read -The--; line #9, "lhalide" should read halide Column 13, line 7, before "containing", layer-- should be inserted; line 33, "phythalate" should read --=-phthalate--; lines t7- t8, "stainles-steel" should read -stainles's-steel--; line #8, "ay" should read -at-; I y p line 55 "immemmrsed" should read --immersed-- Column l t, lines 17-18, portions of the negative during lamination) A 1.0 percent aqueous" should be deleted since it repeats words from lines 15-16; lines t3-Mt, "overcoated with a gel layer (150 g.,/m. should be deleted since it repeats words from line #3.; Column 15', line 29, "formation" (2nd occurrence) should be deleted; Column 18, line #7, "7" should read -l7-..

an cats this [SEAL] thirtieth ay 0; September1975 v A ttes r.-

RUTH C. MASON Arresting Officer C. MARSHALL DAMN (ummr'ssr'mur uj'PaIenrs and Trademarks 

2. A receiver element according to claim 1 wherein said cobalt(III) complex is present in a concentration of at least 1.0 percent by weight of said hydrophilic colloid based on cobalt.
 3. A receiver element according to claim 1 wherein said unhardened hydrophilic colloid consists essentially of gelatin at a concentration of at least 20 mg./ft.2.
 4. A receiver element according to claim 1 which contains a nonmetallic opacifying material dispersed in said hydrophilic colloid.
 5. A receiver element according to claim 1 which contains an incorporated silver halide developing agent.
 6. A receiver element according to claim 1 which contains a photographic color coupler.
 7. A receiver element according to claim 1 wherein said cobalt(III) ion complex has a net charge of +3.
 8. A receiver element according to claim 1 wherein said cobalt(III) ion complex contains at least 3 ammine ligands.
 9. A receiver element according to claim 1 wherein said receiver element is coated on a hydrophobic support.
 10. A receiver element according to claim 1 which contains a carbon opacifying agent in a concentration to provide a density of at least 0.5.
 11. A photographic receIver element comprising a support having coated thereon at least 5 mg./ft.2 of an unhardened hydrophilic colloid which consists essentially of an unhardened gelatin having a melting point of less than 150* F. and wherein said element contains a cobalt(III) ion complex in a concentration of at least 1.0 percent by weight of said gelatin based on cobalt, wherein said cobalt(III) ion complex has a coordination number of 6 and contains at least 3 ammine ligands.
 12. A photographic receiver element according to claim 11 which is substantially free of silver halide.
 13. A photographic receiver element according to claim 11 which comprises an opacifying material in a quantity sufficient to provide a density of at least 0.5.
 14. A photographic receiver element according to claim 11 which contains carbon black dispersed in said gelatin.
 15. A photographic receiver element according to claim 11 wherein said cobalt(III) ion complex is a cobaltic hexammine ion complex.
 16. A photographic receiver element according to claim 11 wherein said hydrophilic colloid is an unhardened gelatin at a concentration of 20 mg./ft.2 to about 2,000 mg./ft.2.
 17. A photographic receiver element comprising a support having thereon at least one layer containing an unhardened hydrophilic colloid and at least one other layer containing an unhardened hydrophilic colloid and an opacifying material, and wherein said element contains at least 0.5 mg./ft.2 of a cobalt (III) ion complex and wherein said element contains at least 5 mg./ft.2 of unhardened hydrophilic colloid and said hydrophilic colloid has a melting point of less than 150* F. and is capable of being hardened with formaldehyde to provide at least a 20* F. melting point differential between hardened and unhardened areas.
 18. A photographic element according to claim 17 wherein said support has coated thereon, in sequence, 1) said layer containing unhardened hydrophilic colloid and 2) said layer containing said unhardened hydrophilic colloid and said opacifying material.
 19. A photographic receiver element according to claim 7 wherein said opacifying material is carbon black.
 20. A photographic receiver element comprising a support having thereon at least one layer containing an unhardened hydrophilic colloid and at least 0.5 mg./ft.2 of a cobalt(III) ion complex and at least one other layer containing an unhardened hydrophilic colloid and an opacifying material, wherein said element contains at least 20 mg./ft.2 of unhardened hydrophilic colloid and said hydrophilic colloid has a melting point of less than 150* F. and is capable of being hardened with formaldehyde to provide at least a 20* F. melting point differential between hardened and unhardened areas.
 21. A photographic receiver element according to claim 20 wherein said unhardened hydrophilic colloid consists essentially of unhardened gelatin. 